Imaging systems such as printers, fax machines, and copiers are virtually omnipresent, and can be found in homes and offices worldwide. The development of such systems has facilitated improvements in communication that have in turn fostered an enormous change in the way people live and work. Telecommuting, paperless offices, and intra-office networks represent but a few examples of the advancements that have been made possible by modern imaging systems.
Imaging systems typically create printed images by transferring imaging medium, such as toner, to a sheet of material via a transfer assembly. In some known imaging systems, transfer assemblies are typically provided as pressure roller systems.
A variety of pressure roller systems are known that provide a multitude of functions for printing mechanisms, such as a printer fusing mechanism for fusing toner to print media in a laser printer or copier. The printer fusing mechanism melts carefully positioned toner particles, utilizing heat and pressure, onto print media with the printer fusing mechanism. However, both toner contamination and pressure roller material degradation can adversely affect the print quality of the output product.
For example, the type of print media affects the success of the fusing process. Where the print media is of a type where fusing the toner to the media is more difficult than with other types of print media, some of the toner may be transferred to a heated roller, and then back to a pressure roller of the printer fusing mechanism. Such unwanted transfer is referred to as toner contamination within the system. Once toner contamination is transferred to the pressure roller the contamination can be picked up by the back page of print media passing the pressure roller, or the contamination can be transferred again to the heated roller, and can randomly appear on the front page of print media passing the heated roller. In either case, the quality of the printed output from the printing mechanism is potentially degraded where toner contamination is present in the printing mechanism system. Additionally, contamination can cause print media to adhere to the roller and jam the fusing mechanism. Such jams are often serious enough to require a service call.
Furthermore, in order to output a product using the printer fusing mechanism, the pressure roller is necessarily subject to numerous heating and cooling cycles that can degrade the pressure roller material. Degradation of the pressure roller material can cause cracking and/or wrinkling of the pressure roller material along the length of the pressure roller. When the pressure roller material is sufficiently degraded, the output product is adversely affected, and print quality is reduced.
Such known defects as toner contamination and pressure roller material degradation both adversely affect the output product print quality and in fact are only discovered by a reduction in the quality of the output product print quality. Currently, in an attempt to determine the nature of the defect, a number of "cleaning pages" are printed with the printer, or copier. Cleaning pages are typically provided as blank pages, or can incorporate precise patterns of printed material. If toner contamination is present on the pressure roller and/or the heater roller, successive cleaning pages can affect a decrease in the amount of toner contamination present. If the print quality is not improved once the cleaning pages have been printed, then replacement of the fusing mechanism is generally recommended, as it is assumed that the defect cannot be corrected by cleaning. Often, an insufficient number of cleaning pages are run through the printer or copier, and the fusing mechanism is needlessly replaced, affecting both printer downtime and warranty or service costs. Further, the number of output products adversely affected by a reduction in printer quality, as well as the number of cleaning pages needed to effectively clean the pressure and heated rollers, could be reduced if a defect in the printer fusing mechanism could be more readily detected.